The present invention relates to x-ray imaging, and more particularly, to needle tracking in 2D fluoroscopic image sequences.
In image guided abdominal interventions, needle tracking has important applications. Needle tracking provides the positions of needles in fluoroscopic images of the abdomen. Needle tracking can be used to compensate for breathing motion in fluoroscopic image sequences and to guide real-time overlaying of 3D images, which are acquired prior to an intervention. Needle detection and tracking in fluoroscopic image sequences is challenging due to the low signal to noise ratio of the fluoroscopic images, as well as the need for real-time speed and a high level of accuracy. Furthermore, different types of needles typically show a large variation in shape and appearance in fluoroscopic images, thus increasing the difficulty of implementing automatic needle tracking.
Since a needle is essentially a one-dimensional thin structure, tracking methods that use regional features, such as holistic intensity, textures, and color histograms, cannot track a needle well in fluoroscopic images. Active contour and level set based methods rely heavily on intensity edges, so they are easily attracted to image noise in fluoroscopic images. Considering the noise level in typical fluoroscopic images, conventional methods cannot deliver the desired speed, accuracy, and robustness for abdominal interventions. Accordingly, a robust, efficient, and accurate method of needle tracking is desirable.